A current trend in the automotive industry is to introduce active safety systems for avoiding or mitigating collisions. Some of the introduced active safety systems are aimed at avoiding or mitigating forward collisions between a vehicle hosting such a system and an oncoming vehicle. These active safety systems have a potentially large positive impact on accident statistics. Forward collisions between two vehicles may, for example, be due to intentional or unintentional lane changes or to the fact that any of the drivers of the vehicles does not drive completely on the correct side of a road.
In known active safety systems for avoiding or mitigating a forward collision between a host vehicle and an oncoming vehicle, a vehicle forward collision threat evaluation system performs an evaluation of the vehicle forward collision threat before any action in order to avoid or mitigate a collision is executed. Normally, the vehicle forward collision threat evaluation systems utilize one or more sensors based on technologies such as RADAR (RAdio Detection And Ranging), LIDAR (Light Detection And Ranging), LASER (Light Amplification by Stimulated Emission of Radiation) and cameras in order to establish the presence of an oncoming vehicle and estimate parameters such as the distance between the oncoming vehicle and the host vehicle, lateral and longitudinal velocity of the oncoming vehicle, and lateral and longitudinal acceleration of the oncoming vehicle.
Typically, the estimated parameters are utilized for prediction of a future path of the oncoming vehicle. The predicted future path of the oncoming vehicle is then compared with a predicted future path of the host vehicle in order to check if a collision between the host vehicle and the oncoming vehicle is likely to occur, i.e. in order to decide whether there is a vehicle forward collision threat or not. In case it is decided that a vehicle forward collision threat exists, a collision avoidance functionality may be executed by the active safety system. For example, a Forward Collision Warning (FCW) functionality, a Collision Mitigation by Braking (CMbB) or an autonomous steering intervention of the host vehicle may then be executed.
Forward Collision Warning (FCW) is a function that warns the driver in case a collision with a target object seems likely. Collision Mitigation by Braking (CMbB) is a function that automatically applies braking in case a collision with a target object is unavoidable.
However, the above mentioned sensors, which are utilized in order to establish the presence of an oncoming vehicle and to estimate the above mentioned parameters thereof, provide estimations of the lateral velocity and the lateral acceleration of the oncoming vehicle with limited accuracy. This implies in turn that the accuracy of the predicted future path of the oncoming vehicle also is limited since the prediction of the future path is based on the lateral velocity and lateral acceleration (as well as other parameters) estimated by means of any of those sensors.
Furthermore, in order for an action executed in order to avoid a collision, e.g. an FCW, CMbB or autonomous steering intervention, to be effective, it has to be initiated a few seconds (e.g. about three seconds) before an estimated collision time point (or passing time point). Thus, the above mentioned vehicle forward collision threat evaluation has to be performed a few seconds before an estimated collision time point. Thereby, the future path of the oncoming vehicle, which is utilized for comparison with the path of the host vehicle in the evaluation, has to be predicted a few seconds before an estimated collision time point. However, there is an uncertainty of future maneuvers of the oncoming car, i.e. many things can happen during the time between the time point of prediction of the future path of the oncoming vehicle and the time point when the vehicles reach each other, resulting in another actual path of the oncoming vehicle than the predicted path.
Thus, since the predicted future path of the oncoming vehicle has limited accuracy and since there is an uncertainty of future movements of the oncoming vehicle in accordance with the above, the conventional vehicle forward collision threat evaluation, which is based on a comparison of the predicted future path of the oncoming vehicle and the predicted future path of the host vehicle, may easily turn out wrong. For example, it may result in false alarms and interventions. Consequently, there is still a need for another improved approach in automotive forward collision threat evaluations.